What do these words on my Pentagram necklace mean?

It is one word Tetragrammaton. Which translated means literally 'four lettered name'. and refers to the four lettered name of God which is never spoken but is spelled YHVH or in the Hebrew - Yod Heh Vav Heh. This name is used quiet a bit in qabalistic magik. The symbols are planetary and astrological signs, and Hebrew letters.